How to check your Mac for viruses and stay secure

Computer viruses hold a sweet spot between boring, everyday occurrences, dating back to the 70s, and dramatic, science fiction fueled monsters that will haunt us in our new information-driven world.

One may ask, “Do you need antivirus to protect your Mac?” The reality is, all computers, even Macs, are vulnerable to malware (short for malicious software). While Apple takes a lot of security precautions, how secure your Mac is depends on your knowledge of how to check for viruses and how to remove them.

Whether you want to know how to remove virus from MacBook Pro, MacBook Air, or iMac, learning to keep your information safe first is necessary and easy, with a few tips from the professionals.

How to scan your Mac for a virus

Why checking your Mac for viruses is important? If a computer virus was the only thing to watch out for, this world would be a simpler place. Malware, adware, spyware, malicious files, worms, trojans, phishing software, you name it, you should check for it. The old way of thinking was that because there are more PCs than Macs in the world, the “virus people” would focus on them instead of Macs. But, we’re not in the 2000s anymore. In fact, in 2018, Apple moved to the fourth position in global laptop shipments. This means, Macs are no longer shiny white boxes that are meant for fun and entertainment.

Not only do we run our businesses off Apple devices and different versions of macOS but we also store family photographs, send out sensitive info — and, thanks to cloud computing, each device is synchronized. Unfortunately, this means your Mac could be a far juicier target than the PC sitting in some corner cubicle.

Know what a Mac virus is

Most of us are familiar with recognizing what a virus looks like thanks to its atrocious design and alarming vocabulary. However, not all viruses take the shock-and-scare approach to getting on your Mac. The latest adware could look like an Adobe Flash Player installer, but is, of course, fake. Not only does it trick you into thinking it's something as normal as Flash, but the installed adware then pretends to be a virus scanner. It shows you bogus problems and encourages you to fix them by giving over sensitive information.

Other forms of viruses could look like Microsoft Office files (e.g. Excel sheets, Word documents), Adobe Photoshop add-ons, as well as music and movie files that you get from BitTorrent or other file sharing programs. But the most common file format that a virus takes is a .dmg file, because it was created by Apple itself to help install good software on your computer. Your task in securing your Mac is to look out for .dmg files showing up when you’re trying to install something. If you’re ever trying to download something you know is supposed to be an image, music, movie, or document, but you get a .dmg file instead — that is as red as a red flag gets in terms of viruses. Do yourself a favor and delete that file immediately.

Keep Mac virus sources in mind

When it comes to having your Mac infected by a virus, we probably expect the attack to come from a stranger. Truth be told, a lot of viruses come from our friends, family, and colleagues, who unfortunately became the primary victim and are now unintentionally passing their viruses to you.

A popular malware virus of 2017 was embedded into a Word document — a Mac Word file, not a PC one. In 2018, Apple discovered flaws in their Intel processor chips that could lead to two kinds of very ambitious strains of Mac viruses too. It’s wild to think that even iPads and iPhones can contract malware.

How to check for malware

In an ideal world, scanning for viruses and other malware should be automatic and happen nearly continuously. In reality, you can consider yourself reasonably safe if you scan your Mac close to once a week. Fortunately, there are quite a few ways to make sure you are as protected as possible.

A good start to checking your Mac for viruses is to see whether you have applications installed that you don’t recognize. Go to the Applications folder via Go > Applications in Finder or using the shortcut Shift + Command + A. Scroll through the list and delete any unknown applications. Then empty the trash.

The second step you should do is check for browser hijackers and adware extensions. Go to Safari > Preferences. See what the Homepage URL is currently set to and correct if needed. Then proceed to the Extensions tab and uninstall any you don’t recognize, as they could spy on you, save your private data, and redirect you to their malicious websites.

How to run a Mac virus scanner and stop viruses from stealing your information

It’s a common misconception that viruses only happen to people who are gullible, ignorant, or technologically illiterate. The stigma is that hackers prey on people, when in reality, they prey on behavior.

Our basic assumption with Macs is that we expect Apple and our applications to have done all the security work for us. In truth, every user has to adjust their own behavior when using their Mac.

Do you use public WiFi? Consider getting a Virtual Private Network (VPN) to encrypt the connection between your laptop and the external network. Shimo is a great VPN manager app that will help you here. While using it, raw information (whether sensitive or not) can’t be fed to any malicious programs lurking on your Mac, and hackers on the same network won’t be able to decode anything you’re working on.

Speaking of encryption, Macs using OS X Lion or later come with the option to encrypt their hard drives using FileVault 2. Although encryption won’t prevent viruses from entering your computer (for that, you’ll need a scanner), it would still be very helpful in stopping viruses from stealing your information. To turn on FileVault:

Go to System Preferences

Select Security & Privacy

Navigate to the FileVault tab

Choose Turn On FileVault

Keep your Mac secure and virus-free

Trademark signs of something being wrong with your Mac: slow processing memory, a bloated disk space, intense CPU usage, and network speed lag. Unfortunately, viruses don’t live in an easy-to-find location like your computer’s desktop. They can be embedded within an application, most notably, your favorite web browser, where it’s easier for them to view what you’re viewing and track what you’re typing. If you kept on seeing weird websites taking over your search bar, it's a sign that your browser has been hijacked. Other applications can get corrupted or infected too, especially if they have particularly weak security systems. Another example could be an email app you use or an open-source application that is behind on their patch upgrades.

If you think one of your applications is infected, a typical knee-jerk reaction would be to delete the whole thing and redownload it. Often, this will do the trick, but there are simpler solutions available. Clearing the application's cache should always be your first step, and, if there are optional hidden files, consider removing them as well.

To remove any application’s cache and get rid of Mac malware from the Library folder:

Use the shortcut Shift + Command + G to Go to Folder

Type ~/Library/Caches and choose Go

Delete any particular files inside the folder

If you are unsure about deleting cache files manually, use an app like CleanMyMac X:

Launch CleanMyMac

Go to System Junk and click Scan

When the scan is complete, choose Review Details

Select User Cache Files and pick the caches you’d like to delete

Click Clean

In addition, CleanMyMac now features a Malware Removal function, using which should become your weekly habit.

In CleanMyMac, choose the Malware Removal tab

Click Scan

Follow the instructions given. Hopefully it should say your Mac is clean most of the time.

Unfortunately, not all viruses are easy-to-understand files that just sit on your computer. Sometimes they are root certificates that intercept your passwords and messages, and send a copy to hackers. To effectively secure yourself from this, only download apps with valid developer certificates. Which ones are those? It’s hard to know but Apple built a feature that could help you here.

You are well on your way to being protected from malware now. But, the truth is, simply avoiding viruses is not enough. You need to be proactive — it’s time to get a virus scanner.

Scan viruses like a pro

If you want complete Mac security, there is no better tool than CleanMyMac X, which can effortlessly check for all the latest viruses, malware, spyware, and more. Just launch the app on the regular basis and click the Smart Scan option to inspect your Mac for any suspicious activity, besides other suggested features for optimization and cleaning out old files.

Remove viruses from Mac completely

Using a tool like CleanMyMac makes getting rid of viruses, of all shapes and formats, very easy. After the scan, it tells you what it’s found and gives you the option to remove it completely right then and there. Additionally, it will give you all kinds of other great options on how to optimize your Mac’s performance.

As mentioned above, hackers who want to steal your information don’t target you specifically, they target your behavior. So, with this in mind, change your behavior when it comes to using your Mac in potentially unsafe ways. Recognize that viruses come and go, all the time, and across many different file formats. If you get a virus, you’re not ruined.

Arm your computer with encryption tools (like FileVault and a VPN), so that your information can’t be stolen. Practice a healthy dose of skepticism when downloading files. But, most importantly, get professional apps that bring you the most results, like CleanMyMac or Shimo — all of which are available on Setapp for your to try free. So get a scan now and see what it says.